The present invention relates to processes for producing cycloalkenyl derivatives from the reaction of acrolein, methacrolein and alkyl vinyl ketone, all formed in situ, with conjugated dienes in good yields.
The Diels-Alder reaction is well known in the field of organic chemistry, and the classic example thereof is the reaction of a conjugated diene with a conjugated alkylene carbonyl compound to provide a cyclohexene derivative. Since the original reaction was set forth, there have been many variations of the reaction.
U.S. Pat. No. 3,341,601 issued on Sept. 12, 1967, relates to a process for producing Diels-Alder adducts of conjugated dienes and carbonyl compounds, wherein the adducts are produced by contacting a reaction mixture comprising a conjugated diene and a carbonyl compound having at least two alpha-hydrogen atoms with a condensation-dehydration catalyst at elevated temperatures according to the following reaction: ##EQU1## Although an in-situ formed methacrolein material is shown to be produced and act as a dienophile in the disclosure of U.S. Pat. No. 3,341,601, the dienes used in this reaction are relatively simple in nature.
Although the reaction of long chain aldehydes with formaldehyde in the presence of an amine catalyst is disclosed in U.S. Pat. No. 3,463,818, no suggestion of the carrying out of a Diels-Alder reaction is set forth therein. U.S. Pat. No. 3,463,818 relates to a process for producing alpha-methylene and alpha-methyl aldehydes and alcohols by reaction, in the presence of an amine catalyst, an aldehyde such as citronellal with formaldehyde.
U.S. Pat. No. 2,373,568 shows the Diels-Alder reaction of methacrolein and cyclopentadiene under pressure at about 140.degree.C to provide a material with a camphoraceous aroma and the further reaction of the Diels-Alder product with acetone and sodium methylate to provide a product with a floral-type odor. Vaughan et al. in J.A.C.S. 74, 5355 shows the reaction of mesityl oxide and cyclopentadiene produced in situ by thermal depolymerization of the dimer to provide an unsaturated ketone by carrying out the reaction at 160.degree.C for 12 hours to provide 21% yield, based upon mesityl oxide.
Chemical Abstracts 47, 12271e shows a diene condensation at 160.degree.C in the presence of pyrolgallol.
Chemical Abstracts, Vol. 56, 4692c discloses the Diels-Alder reaction of allo-ocimene with appropriate carbonyl compounds such as acrylonitrile to yield naphthalene derivatives in the presence of hydroquinone at 160.degree.-200.degree.C for a period of time of from 21/2 hours up to 6 hours in 50-71.5% yields.
Acrolein and allo-ocimene have been shown to react to form Diels-Alder adducts in the presence of hydroquinone by B. A. Arbuzov and A. R. Vil'chinskaya (State Univ., Kazan). Zhur. Obshchei Khim. 31, 2199-204 (1961).
A. R. Vil'chinskaya and B. A. Arbuzov, Voprosy Khim. Terpenov i Terpenoidov, Akad. Nauk Litovsk, S. S. R., Trudy Vsesoyuz, Soveshchaniya, Vil'nyus 1959, 201-7 (Pub. 1960) also show reaction products of crotonaldehyde with allo-ocimene (also see Vol. 55, Chemical Abstracts, 16495d). The Diels-Alder reaction of allo-ocimene with acrolein or crotonaldehyde is also set forth in Vol. 29, Chemical Abstracts 6888.sup.6 (Abstract of Berichte 68B, 1435- 8 (1935). Also suggested in the Berichte article is the condensation of the thus produced reaction products with acetone and other ketones to form "odoriferous ionone-like compounds". U.S. Pat. No. 3,067,244 discloses, interalia, the catalyzed condensation of cyclopentadiene with acrolein.
British Pat. No. 896,039 entitled "Method of Producing Derivatives of the 1,1-Dimethyl-Octahydronaphthalene Series" discloses the generic process: ##SPC4##
wherein R.sub.2, R.sub.3 and R.sub.4 are disclosed to be same or different hydrogen atoms or alkyl and R.sub.1 is disclosed to be hydroxy, alkyl or alkoxy. The British patent discloses this process to be useful for producing products "resembling the well known class of violet perfumes". Indeed, Example 5 of the British Patent alleges that the compound 1,1,6,6-tetramethyl-7-ketomethyl-octalin produced by (1) reacting myrcene and mesityl oxide thermally followed by (2) subsequent cyclization, has a pleasant "woody ambergris smell".
Further, cyclization reactions of Diels-Alder adducts of myrcene and a dienophile are set forth in U.S. Pat. No. 3,076,022. This patent discloses interalia, preparation of the thermal Diels-Alder adduct of myrcene and methyl isopropenyl ketone and subsequent acid cyclization to a product said to possess "an intense ambergris-like note".
Ohloff (Chemistry of Odoriferous and Flavoring Substances) pp. 185-240 (at page 192) Fortschritte & der Chemischen Forschung Vol. 12, Part 2, 1969, discloses a compound having the structure: ##SPC5##
Ohloff indicates that materials of this nature have "resiny odors" like olebanum, with amber type undertones.